Pump assemblies include an intake, an outtake, and a motor operable to drive a propeller so as to circulate fluids through a system. Pump assemblies are commonly attached to a conduit interconnecting the intake to the outtake so as to form a closed system. Many pumps use an electric drive such as a magnet and stator for turning the propeller.
The magnet is housed in the rotor. The rotor includes an inner peripheral wall encircling a shaft. Fluids are delivered to the surface of the shaft so as to provide lubrication for facilitating rotation of the rotor. It is also known to form a passageway on the inner peripheral wall of the rotor so as to provide a passageway in communication with the shaft. The passageway extends between the intake and the outtake. The passageway provides a path for fluids which flow along the shaft so as to help cool the pump and maintain the pump at an optimal operating temperature.
However, rotation of the propeller creates air bubbles in the fluids and in some cases these air bubbles are sucked through the passageway. In certain operating conditions there is insufficient pressure at the outtake and bubbles are entrapped in the passageway. Thus, fluid is not circulated along the outer surface of the shaft and the rotor can seize as the operating temperature of the shaft increases or alternatively corrosion sets in.
Accordingly, it remains desirable to have a pump assembly that can draw the air from the shaft so as to maintain flow of the fluid along the outer surface of the shaft under various operating conditions of the pump. It also remains desirable to have a pump assembly having an impeller operable to draw air bubbles from the shaft that is actuated by the same drive actuating the propeller.